#2213 Test erroneous union queries with different numbers of yields

In general, this approach of asserting that an exception is thrown is
far from the best because it ignores potential exceptions that may be
thrown for unexpected reasons. Being more specific and expecting only a
certain type of exceptions doesn't work either since the exception gets
rethrown at some higher level, effectively becoming a cause of another
exception. Should we be making assertions about the stack trace at this
point? I don't think so.

platform-dao/src/test/java/ua/com/fielden/platform/entity/query/fetching/EntityQuery3ExecutionTest.java

@@ -27,6 +27,7 @@
 import static org.junit.Assert.*;
 import static ua.com.fielden.platform.entity.query.fluent.EntityQueryUtils.*;
 import static ua.com.fielden.platform.test_utils.TestUtils.assertNotThrows;
+import static ua.com.fielden.platform.test_utils.TestUtils.assertThrows;
 
 public class EntityQuery3ExecutionTest extends AbstractDaoTestCase {
     private final IEntityAggregatesOperations aggregateDao = getInstance(IEntityAggregatesOperations.class);
@@ -1105,6 +1106,15 @@ public void nonNulls_can_be_compared_to_nonNulls_in_join_conditions() {
         final List<EntityAggregates> entities = co(EntityAggregates.class).getAllEntities(from(query).model());
     }
 
+    @Test
+    public void union_of_queries_with_different_numbers_of_yields_fails() {
+        final var q1 = select().yield().val(200).as("x").modelAsAggregate();
+        final var q2 = select().yield().val(100).as("x").yield().val(300).as("y").modelAsAggregate();
+        final var union = select(q1, q2).yieldAll().modelAsAggregate();
+
+        assertThrows(() -> co(EntityAggregates.class).getAllEntities(from(union).model()));
+    }
+
     @Override
     public boolean saveDataPopulationScriptToFile() {
         return false;

platform-pojo-bl/src/test/java/ua/com/fielden/platform/test_utils/TestUtils.java

@@ -68,4 +68,14 @@ public static void assertNotThrows(final ThrowingRunnable runnable) {
         }
     }
 
+    public static void assertThrows(final ThrowingRunnable runnable) {
+        try {
+            runnable.run();
+        } catch (final Throwable $) {
+            return;
+        }
+
+        fail("Expected an exception to be thrown but nothing was thrown.");
+    }
+
 }